[TowerTalk] Impact of high water table levels on antennas
W4EF at dellroy.com
Sun Nov 3 17:12:16 EST 2013
KS8S/AD8P had a contest station in Deshler, Ohio in the mid 80's (about
1 hour South of Toledo). With just a ~100' shunt-fed tower they seemed
to have a stand out signal on 160 meters compared to others in the area
with similar setups. Dean KS8S mentioned they had a very high water
table in that area. Also, I remember noticing that there was a region of
higher than average conductivity on the FCC soil conductivity map in
that part of Ohio. Not enough for a firm scientific conclusion, but it
sure seemed like Dean had some sort of magic dirt under his low-band
73, Mike W4EF.......................
On 11/3/2013 11:42 AM, GARY HUBER wrote:
> I have a similar situation. My QTH is on a glacial moraine about a
> tenth of a mile from the crest. There is water bearing clay less than
> thirty inches down and the soil is the black muck left by the glacial
> ponding. To top it off, I've mounted my HV-2 w/160m mod and umbrella
> capacitance hat over two dozen 66 foot radials all over the septic
> leach field. A friend who has operated from ZF2 and C6 numerous times
> says I am very strong using the HV-2 on 40..... I've worked a lot of
> DX with the HV-2 over the septic field over the past 27 years
> including ZL9CI, KH1, KH6, etc.
> I believe the high water table helps me and will help you.... but the
> advantage works also for the 4SQ or any antenna. Probably about 3 dB
> from the Fresnel reflection.
> -----Original Message----- From: Rudy Bakalov
> Sent: Sunday, November 03, 2013 1:02 PM
> To: towertalk at contesting.com
> Subject: [TowerTalk] Impact of high water table levels on antennas
> Ever since I have put up two inv-Vs, one for 80m and one for 160m,
> with their apexes at roughly 90', I have been puzzled by their
> exceptional performance. Ditto for my vertical on 40m. I have done
> tons of comparisons using skimmer data and my signal seems to be
> pretty darn close to the big stations I am using as my benchmark. The
> performance is so good that I have been wondering if I should bother
> with building 4SQs. I have read tons of books on antennas and the
> performance of these two antennas simply does not match what the books
> I shared my thoughts with a friend of mine (a WRTC2014 participant)
> and he shared a similar experience with his station. He recently
> relocated to a new place, about 30 miles from his old place, and his
> antennas at the new place perform significantly better than the old
> location. Same antennas, tower, feed line, and FLAT terrain. His only
> explanation is that the new place had a very high water table that
> somehow impacted antenna performance.
> This is when I realized that I also have a very high water table. Even
> in the driest months of summer, the area around my tower is damp and
> the grass is very green, growing like crazy. This was the obvious
> common element between his and my situations.
> I have not seen anything on high water tables in my antenna books.
> The soil itself is mostly sandy. The impact I believe I am seeing is
> mostly on the lower bands, but I am not sure if this is also the case
> on the upper bands as at 105' my antennas are a bit too high.
> Is there any rationale in our thinking? Can high water table explain
> better than expected performance from low band antennas? If so, what
> is the theory behind it and how do I take advantage of it? If not, any
> other suggestions for why the antennas work so well?
> Rudy N2WQ
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